1. Technical Field
The invention relates to systems and methods of measuring and testing. In particular, the invention relates to temperature sensors and measuring with temperature sensors.
2. Description of Related Art
Temperature is often an important system parameter to measure or monitor. In particular, temperature is often monitored to one or more of control an operational characteristic, improve efficiency and assure the safe operation of a device or system. For example, temperature may be measured to determine if a device is operating within a range that is deemed acceptable. If the temperature is determined to be either outside of the acceptable temperature range or exhibiting abnormal fluctuations, steps can be taken to adjust the temperature, for example by initiating either cooling or heating of the device. Alternatively, an operational characteristic of the device (e.g., power consumption) may be altered to maintain an acceptable operating temperature of the device. In other examples, system parameters of thermodynamic systems such as turbine engines or internal combustion engines can be optimized based on the real-time temperature information to achieve one or both of high efficiency and best performance. In yet other examples, temperature may be monitored to characterize an operational state or condition of the device or system. For example, a system may undergo an increase in temperature that, when a predetermined temperature is reached, indicates that the system has reached a goal state or condition. Monitoring or measuring the system temperature may be used to determine whether the goal has been achieved, and further may provide feedback to a controller that progress is being made by the system towards the goal.
Unfortunately, measuring temperature of a device or system may present certain challenges in many practical situations. For example, it may be useful to directly measure a temperature internal to a device instead of a surface temperature of the device. The internal temperature may be more meaningful than the surface temperature for various monitoring situations, for example. However, monitoring an internal temperature may present various practical difficulties, especially when it is difficult or even impossible to run wires into the device or system. For example, the device may be housed in a sealed container. Passing wires associated with a conventional temperature sensor (e.g., a thermal couple) through the container to measure the internal temperature may not be practical or even possible in certain situations. In other examples, such as temperature distribution mapping within a device, providing sensor leads to and from multiple temperature sensors at numerous points within the device may be impractical, may interfere with the mapping itself, and even may be detrimental to device operation. In yet other examples, a target of the temperature measurement may be a moving part or component of a system (e.g., a turbine blade rotating within a jet engine). Monitoring the temperature of such a moving target may not be practical using a wired temperature sensor, for example.